Many systems (such as electrically-operated heat-pump air-conditioning systems and natural-gas powered heating and air-conditioning systems), industrial processes (such as petro-chemical refining processes or steam-boiler systems), and various pumping systems, involve the use of flowing gases or liquids which under normal operating conditions have pressure levels that are substantially constant or that vary within relatively small ranges. Thus, a discontinuity in such a fluid pressure level is indicative of some kind of malfunction, which for safety or efficiency reasons should be detected whenever it occurs, in order that appropriate correction measures may be taken.
Accordingly there has been a need for a simple, compact, reliable and inexpensive real-time pressure discontinuity analysis system capable of detecting such discontinuities and alerting either a human operator or another automatic correction system to the occurrence of a pressure discontinuity.
While relatively expensive alarm systems of this type are known, these tend to be complicated and to operate by indirect sensing methods which require sophisticated data-processing procedures and techniques in order to be of practical utility. For example, the "Method of and System for Detecting Misfire in Internal Combustion Engine" U.S. Pat. No. 4,083,234, issued Apr. 11, 1978 (and assigned to Nissan Motor Co., Ltd. of Japan), involves two separate indirect transducers, namely an acoustic transducer, such as an earphone receiver placed near the output of the engine exhaust gas, together with a rotary electromechanical engine-speed responsive frequency generator which produces a frequency variable proportional to the output speed of the engine. Furthermore, the signals from these two separate transducers must be processed by a fairly complicated electromechanical frequency analyzer (involving four separate band-pass filters, and two rotary contact mechanical elements operated at variable frequencies dependent upon engine speed).
Accordingly there has been a need for a more direct pressure-discontinuity analysis system, which utilizes only one transducer, namely a pressure transducer, and which operates successfully regardless of the values of other related variables (such as engine speed, in the case of automobile engine misfiring detection systems).
Also there has been a need for an analysis system which does not include any rotating mechanical parts, and whose mechanical aspects are limited to the simple flexing of a diaphragm of low mechanical hysteresis, which simplification greatly improves reliability and extends lifetime durability without need of scheduled service and essentially eliminates the possibility of breakdown-mandated repairs.